Various techniques currently exist for testing antennas or determining a radar cross section (RCS) of an object such as, for example, a small-scale aircraft. Far-field range testing involves placing a test article at a relatively long distance away from instrumentation. Since far-field range testing requires a large amount of space due to the long distances between the test article and the instrumentation, outdoor facilities are typically used. Compact ranges are an alternative to traditional far-field ranges. Any test that is capable of being accomplished on a far-field range may also be done using a compact test range. A compact range allows an operator to test indoors, thereby avoiding issues such as unfavorable weather conditions that are often encountered when testing outdoors.
In compact range testing, a horn antenna conveys radio waves towards a parabolic reflector. The horn antenna is often referred to as a feed horn. The feed horn is placed at the focus of the parabolic reflector. The reflector may be a portion of the parabola that is offset from the axis of the parabolic reflector. A radio wave originating at the feed horn may include an infinite number of rays that are reflected off of a surface of the reflector. The rays of the radio wave are reflected from the surface of the reflector are then directed towards the test article. The rays of the radio wave are reflected off of the surface of the reflector are each parallel to one another, and are aligned with a horizontal axis. Moreover, the rays of the radio wave define a path from the feed horn to the axis of the paraboloid, where each path of each ray is equal in length to the other remaining rays of the radio wave. Since the rays of the radio wave are horizontal, parallel, and equal in length with respect to one another, a flat phase front is created within the testing zone. The flat phase front is representative of far-field conditions. Therefore, although the testing zone is positioned at a near-field distance from the reflector, the compact range testing arrangement is capable of producing the flat phase front created in far-field testing.
Although compact range testing provides numerous advantages and benefits, there are still challenges that exist. Specifically, the test article is rotated during compact range testing to create a matrix of measurements. However, the test article needs to be re-positioned each time a measurement is collected. Therefore, compact range testing may be cumbersome and may also take a relatively long time to complete.